Picture encoding apparatus, picture encoding method, picture encoding and transmitting method, and picture record medium

ABSTRACT

On a decoding side, parameters (minimum value MIN and dynamic range DR) are optimized in such a manner that a decoded error of original signal values and restored values becomes minimum. A maximum value detecting portion 2 detects the maximum value MAX of pixels of each block composed of (3×3) pixels. Likewise, a minimum value detecting portion 3 detects the minimum value MIN. A subtracting portion 4 generates a dynamic range DR. A subtracting portion 5 subtracts MIN from each of input pixel values y and generates normalized values. A step width calculating portion 6 calculates a quantizing step width Δ with DR. A quantizing portion 7 generates quantized values x (each of which is composed of 4 bits) with Δ. A least squares method based estimating portion 8 generates decoded values y&#39; with y and x and obtains an optimized dynamic range DR&#39; and an optimized minimum value MIN&#39; in such a manner that the sum of square of an error (y&#39;-y) becomes minimum. A framing portion 11 frames x, DR&#39;, and MIN&#39; and records the framed data on a record medium 15 through an error-correction-code adding portion 12, a modulating portion 13, and a recording portion 14.

This application is a division of application Ser. No. 08/671,783, filedJun. 20, 1996 now U.S. Pat. No. 5,734,433.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a picture encoding apparatus forencoding a digital picture signal in such a manner that the data amountthereof is reduced, a picture encoding method thereof, a pictureencoding and transmitting method thereof, and a picture record mediumthereof. In particular, the present invention relates to a pictureencoding apparatus for encoding a digital picture signal andtransmitting additional information along with the encoded information,a picture encoding method thereof, a picture encoding and transmittingmethod thereof, and a picture record medium thereof.

1. Description of Related Art

FIG. 1 is a block diagram showing a structure of a picture encodingapparatus that compresses a digital picture signal. The picture encodingapparatus shown in FIG. 1 is an encoding apparatus corresponding to theADRC (Adaptive Dynamic Range Coding) method. The encoding apparatusdivides the input picture signal into blocks and adaptively encodespixels of each block corresponding to the dynamic range of the block.

The ADRC method has been proposed by the applicant of the present patentapplication as U.S. Pat. No. 4,703,352 issued on Oct. 27, 1987(corresponding to Japanese Patent Laid-Open Publication No. 61-14498laid open on Jul. 2, 1986). Next, with reference to FIG. 1, the ADRCmethod will be described in brief. An input picture signal is suppliedform an input terminal 120 to a block dividing portion 121. The blockdividing portion 121 divides the input picture signal into blocks eachof which is composed of for example 9 pixels (3 pixels×3 lines)(hereinafter referred to as a block of (3×3) pixels). The output signalfor each block is supplied from the block dividing portion 121 to amaximum value detecting portion 122 and a minimum value detectingportion 123.

The maximum value detecting portion 122 detects the maximum value MAX ofthe pixel values of the block. The minimum value detecting portion 123detects the minimum value MIN of the pixel values of the block. Themaximum value MAX is supplied from the maximum value detecting portion122 to a subtracting portion 124. On the other hand, the minimum valueMIN is supplied from the minimum value detecting portion 123 to thesubtracting portion 124, a subtracting portion 125, and a framingportion 128.

The subtracting portion 124 subtracts the minimum value MIN from themaximum value MAX and generates a dynamic range DR. The dynamic range DRis supplied to a quantizing step width calculating portion 126 and theframing portion 128. The quantizing step width calculating portion 126calculates a quantizing step width Δ with the dynamic range DR suppliedfrom the subtracting portion 124 and supplies the calculated quantizingstep width Δ to a quantizing portion 127.

The block dividing portion 121 also supplies 9 pixels of the block of(3×3) pixels to the subtracting portion 125. The subtracting portion 125subtracts the minimum value MIN from each of the 9 pixel values. Thus,each pixel value is normalized. Each normalized pixel value is suppliedto the quantizing portion 127. The quantizing portion 127 quantizes thenormalized pixel values with the quantizing step width Δ and suppliesquantized values x to the framing portion 128.

The framing portion 128 frames the dynamic range DR and the minimumvalue MIN supplied as parameters for each block and the quantized valuesx of the 9 pixels of the block and obtains an output signal. The outputsignal is recorded on a record medium such as a disc or transmittedthrough a transmission line.

However, in the case that the quantized values of the block are decodedwith the parameters on the recording side, to minimize a decoded errorbetween original signal values and restored values, it is not assuredthat quantized values of the block are optimally decoded with parametersof a block that have been initially obtained. Occasionally, the decodederror becomes large and thereby the decoded picture may deteriorate.

OBJECT AND SUMMARY OF THE INVENTION

Therefore, an object of the present invention is to provide a pictureencoding apparatus for optimizing parameters that have been initiallyobtained on the encoding side (the parameters are for example themaximum value MAX, the minimum value MIN, or the dynamic range DR in thecase of the ADRC method) so as to decrease the decoded error betweenoriginal signal values and restored values, a picture encoding methodthereof, a picture encoding and transmitting method thereof, and apicture record medium thereof.

To accomplish the above-described object, a first aspect of the presentinvention is a picture encoding method for encoding an input digitalpicture signal in such a manner that the amount of generated data of theinput digital picture signal is reduced, comprising the steps ofdividing the input digital picture signal into blocks each of which iscomposed of a plurality of pixels, encoding the pixels of each of theblocks and generating encoded data and a parameter, and optimizing theparameter generated for each of the blocks in such a manner that the sumof square of an decoded error of the encoded data becomes minimum, apicture encoding apparatus thereof, a picture encoding and transmittingmethod thereof, and a record medium thereof.

A second aspect of the present invention is the picture encoding methodof the first aspect, wherein encoding step comprises the steps ofdetecting the maximum value of the pixels of each of the blocks and theminimum values thereof, detecting a dynamic range that is the differencebetween the maximum value and the minimum value, and quantizing pixelvalues of the pixels that have been normalized with the value of thedynamic range and generating quantized values of the pixels, and whereinthe optimizing step is performed by optimizing the parameter of each ofthe blocks in such a manner that the sum of square of the decoded errorof the quantized values becomes minimum, a picture encoding apparatusthereof, a picture encoding and transmitting method thereof, and arecord medium thereof.

A third aspect of the present invention is the picture encoding methodof the first aspect, wherein the optimizing step is performed byoptimizing at least two of information representing the maximum value,the minimum value, and the dynamic range of the pixels of each of theblocks in such a manner that the sum of square of the decoded error ofthe quantized values becomes minimum, a picture encoding apparatusthereof, a picture encoding and transmitting method thereof, and arecord medium thereof.

As described above, according to the present invention, after parametersof a block are obtained, encoded pixel values are decoded with theparameters. The error between the decoded values and the true values isobtained. Thereafter, the parameters are corrected in such a manner thatthe error becomes minimum. Thus, the error between the original signalvalues and the restored values can be further decreased.

These and other objects, features and advantages of the presentinvention will become more apparent in light of the following detaileddescription of best mode embodiments thereof, as illustrated in theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing a conventional ADRC system;

FIGS. 2A and 2B are block diagrams showing a structure of a pictureencoding apparatus according to a first embodiment of the presentinvention;

FIG. 3 is a schematic diagram showing a structure of a least squaresmethod based estimating portion according to the present invention;

FIG. 4 is a schematic diagram showing a structure of a least squaresmethod based estimating portion according to the present invention;

FIGS. 5A and 5B are block diagrams showing a structure of a pictureencoding apparatus according to a second embodiment of the presentinvention;

FIGS. 6A and 6B are block diagrams showing a structure of a pictureencoding apparatus according to a third embodiment of the presentinvention; and

FIG. 7 is a block diagram showing a structure of a hierarchical encodingapparatus for which a picture encoding apparatus according to thepresent invention is applied.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Next, with reference to accompanying drawings, embodiments of thepresent invention will be described. FIGS. 2A and 2B are block diagramsshowing a structure of a picture encoding apparatus according to a firstembodiment of the present invention. An input picture signal is suppliedfrom an input terminal IN to a block dividing portion 1. The blockdividing portion 1 divides the input picture signal into blocks each ofwhich is composed of (3×3) pixels. Input pixel values y of the 9 pixelsof each block of (3×3) pixels are supplied to a maximum value detectingportion 2, a minimum value detecting portion 3, a subtracting portion 5,and a least squares method based estimating portion 8. Each of the inputpixel values y is composed of 8 bits.

The maximum value detecting portion 2 detects the maximum value of thelevels of the nine pixels of the block of (3×3) pixels and suppliesoutput data as a maximum value MAX to a subtracting portion 4. On theother hand, the minimum value detecting portion 3 detects the minimumvalue of the levels of the nine pixel values of the block and suppliedoutput data as a minimum value MIN to the subtracting portion 4 and thesubtracting portion 5.

The subtracting portion 4 subtracts the minimum value MIN from themaximum value MAX and generates a dynamic range DR. The dynamic range DRis supplied to a quantizing step width calculating portion 6. Thesubtracting portion 5 subtracts the minimum value MIN from each of theinput pixel values y of the 9 pixels of the block of (3×3) pixels andgenerates normalized pixel values of the 9 pixels of (3×3) pixels. Thenormalized pixel values are supplied to a quantizing portion 7.

The quantizing step width calculating portion 6 calculates a quantizingstep width Δ with the supplied dynamic range DR and supplies thecalculated quantizing step width Δ to the quantizing portion 7. Thequantizing portion 7 quantizes the normalized pixel values of the 9pixels of the block as four bits and supplies the quantized values x ofthe 9 pixels of the block of (3×3) pixels to the least squares methodbased estimating portion 8 and a framing portion 11.

Thus, the input pixel values y of the 9 pixels of the block of (3×3)pixels as the input picture signal and the quantized values x of the 9pixels of the block of (3×3) pixels are supplied to the least squaresmethod based estimating portion 8. The least squares method basedestimating portion 8 estimates an optimized dynamic range DR' and anoptimized minimum value MIN' with the input pixel values (true values) yof the block and the quantized values x of the block corresponding tothe least squares method in such a manner that the sum of square of anerror (y'-y) of the decoded values y' and the true values y becomesminimum. In other words, the following relation is satisfied between thedecoded values y' of the input pixel values y and the quantized valuesx.

    y'=x×DR/n+MIN                                        (1)

(where n is the number of quantizing bits)

The optimized dynamic range DR' can be obtained by the following formula(2).

    DR'=n·Δ'                                    (2)

(where Δ' is the optimized quantizing step width)

When the number of pixels of the block is denoted by m, the optimizedquantizing step width can be obtained by the following formula (3).

    Δ'=(m·Σxy-Σx·Σy)/(m·.SIGMA.x.sup.2 -(Σx).sup.2)                              (3)

In addition, the optimized minimum value MIN' can be obtained by thefollowing formula (4).

    MIN'=(Σy-Δ'·Σx)/m               (4)

The optimized dynamic range DR' and the optimized minimum value MIN' aresupplied to the framing portion 11. The framing portion 11 frames thequantized values x supplied from the quantizing portion 7, the optimizeddynamic range DR' supplied from the least squares method basedestimating portion 8, and the optimized minimum value MIN' suppliedtherefrom and supplies the framed signal to an error correction codeadding portion 12.

The error correction code adding portion 12 adds an error correctioncode to the framed signal and supplies the resultant signal to amodulating portion 13. The modulating portion 13 modulates the resultantsignal corresponding to the EFM modulating method or the like. Themodulated signal is supplied to a recording portion 14. The recordingportion 14 records the modulated signal on a record medium 15 such as adisc.

When the modulated signal is transmitted through a transmission line 17,according to the present invention, a transmitting portion 16 is usedinstead of the recording portion 14. The modulating portion 13 modulatesthe framed signal to which the error correction code has been addedcorresponding to a modulating method suitable for data transmission andsupplies the modulated signal to the transmission line 17 through thetransmitting portion 16. Since various framing technologies andmodulating technologies are known, their description is omitted. In thepresent invention, any framing technology or any modulating technologycan be used.

Next, with reference to FIGS. 3 and 4, the least squares method basedestimating portion 8 according to the first embodiment will be describedin detail. FIG. 4 is a circuit diagram showing a real structure forobtaining an optimized dynamic range DR' and an optimized minimum valueMIN' corresponding to the least squares method. FIG. 3 is a circuitdiagram showing a structure for calculating constants necessary for thestructure shown in FIG. 4.

As described above, the data x used in the first embodiment is quantizedvalues of pixels, whereas the data y' is the restored values of the datax. In addition, the true values of the data y' are denoted by y and thenumber of pixels of each block is denoted by m. Thus, the least squaresmethod based estimating portion 8 estimates the optimized minimum valueMIN' and the optimized dynamic range DR' with the pixel values y and thequantized values x for each block corresponding to the least squaresmethod in such a manner that the sum of square of the error (y'-y)becomes minimum.

In FIG. 3, data x is supplied from an input terminal 21 to a register22. Data y is supplied from an input terminal 23 to a register 24. Acounter 25 counts the number of pixels of each block corresponding to aclock. The counted number of pixels m is supplied to a terminal 28through registers 26 and 27.

A multiplying device 29 multiplies the data x (composed of 4 bits)supplied from the register 22 by the data y (composed of 8 bits)supplied from the register 24 and supplies output data (composed of 12bits) as data xy to an adding circuit 31 through a register 30. In theadding circuit 31, the data xy (composed of 12 bits) is supplied to anadding device 31a. The output data of the adding device 31a is suppliedto registers 31b and 31c. The data xy supplied from the register 30 andthe output data of the adding device 31a supplied through the register31b are added by the adding device 31a. The adding circuit 31 suppliesoutput data (composed of 18 bits) as data Σxy to a terminal 33 through aregister 32. In other words, the adding circuit 31 generates Σxy foreach block.

The data x (composed of 4 bits) supplied from the register 22 issupplied to an adding circuit 35 through a register 34. In the addingcircuit 35, the data x (composed of 4 bits) is supplied to an addingdevice 35a. The output data of the adding device 35a is supplied toregisters 35b and 35c. The data x supplied from the register 34 and theoutput data of the adding device 35a supplied through the register 35bare added by the adding device 35a. The adding circuit 35 suppliesoutput data (composed of 10 bits) as data Σx to a terminal 37 through aregister 36. In other words, the adding circuit 35 generates Σx for eachblock.

In addition, the data Δx (composed of 10 bits) is also supplied from theadding circuit 35 to a multiplying device 38. The multiplying device 38squares the data Σx and supplies output data (composed of 20 bits) asdata (Σx)² to a terminal 40 through a register 39.

The data y (composed of 8 bits) supplied from the register 24 issupplied to an adding circuit 42 through a register 41. In the addingcircuit 42, the supplied data y (composed of 8 bits) is supplied to anadding device 42a. The output data of the adding device 42a is suppliedto registers 42b and 42c. The data y supplied from the register 41 andthe output data of the adding device 42a supplied through the register42b are added by the adding device 42a. The adding circuit 42 suppliesoutput data (composed of 14 bits) as data Σy to a terminal 44 through aregister 43. In other words, the adding circuit 42 generates Σy for eachblock.

A multiplying device 45 squares the data x (composed of 4 bits) suppliedfrom the register 22 and supplies output data x² (composed of 8 bits) toan adding circuit 47a through a register 46. The output data of theadding device 47a is supplied to registers 47b and 47c. The data x²supplied from the register 46 and the output data of the adding device47a supplied through the register 47b are added by the adding device47a. The adding circuit 47 supplies output data (composed of 14 bits) asdata Σx² to a terminal 49 through a register 48. In other words, theadding circuit 47 generates Σx² for each block.

In addition, an input terminal 50 is connected to the counter 25 andclear terminals of the registers 31b, 35b, 42b, and 47b. Input terminals51 is connected to clear terminals of the registers 27, 32, 36, 39, 43,and 48. These registers are controlled for each block by signalssupplied to the input terminals 50 and 51.

FIG. 4 shows a conventional structure of a real portion that performsthe least squares method. The number of pixels m is supplied from aterminal 28 to an inverse number calculating circuit 61, a multiplyingdevice 64, and a multiplying device 71. The inverse number calculatingcircuit 61 calculates the inverse number (1/m) of the number of pixels msupplied and supplies the inverse number (1/m) to a terminal 63 througha register 62. The multiplying device 64 multiplies data Σxy suppliedfrom a terminal 33 by the number of pixels m and supplies output data asdata mΣxy to a subtracting device 66 through a register 65.

Data Σx supplied from a terminal 37 is supplied to multiplying devices67 and 74. Data Σy supplied from a terminal 44 is supplied to themultiplying device 67. The multiplying device 67 multiplies the data Σxand data Σy and supplies output data as ΣxΣy to the subtracting device66 through a register 68. The subtracting device 66 subtracts the dataΣxΣy from the data mΣxy and supplies output data as data (mΣxy-ΣxΣy) toa multiplying device 79 through registers 69 and 70.

The multiplying device 71 multiplies data Σx² supplied from a terminal49 by the number of pixels m and supplies output data as data mΣx² to asubtracting device 73 through a register 72. The multiplying device 74squares the data Σx and supplies output data as data (Σx)² to thesubtracting device 73. The subtracting device 73 subtracts the data(Σx)² from the data mΣx² and supplies output data as data (mΣx² -(Σx)²)to an inverse number calculating circuit 77 through a register 76. Asdescribed above, the inverse number calculating circuit 77 calculatesthe inverse number (1/(mΣx² -(Σx)²) of the data (mΣx² -(Σx)²) andsupplies the inverse number (1/(mΣx² -(Σx) ²) to the multiplying device79 through a register 78.

The multiplying device 79 multiplies the data (mΣxy-ΣxΣy) by the data(1/(mΣx² -(Σx)²) and supplies output data as data ((mΣxy-ΣxΣy)/(mΣx²-(Σx)²)) to multiplying circuits 81 and 89 through a register 80. Themultiplying device 81 multiplies data Σx supplied from a terminal 37 bythe data ((mΣxy-ΣxΣy)/(mΣx² -(Σx)²)) and supplies output data as data((mΣxΣxy-(Σx)² Σy)/(mΣx² -(Σx)²)) to a subtracting device 83 through aregister 82.

The subtracting device 83 subtracts the data ((mΣxΣxy-(Σx)² Σy)/(mΣx²-(Σx)²) from data Σy supplied from a terminal 44 and supplies outputdata as data (m(Σx² Σy-ΣxΣxy)/(mΣx² -(Σx)²)) to a multiplying device 85through a register 85. The multiplying device 85 multiplies data 1/msupplied from a terminal 63 by the data (m(Σx² Σy-ΣxΣxy)/(mΣx² -(Σx)²))and supplies output data as data ((Σx² Σy-ΣxΣxy)/(mΣx² -(Σx)²)) that isan optimized minimum value MIN'. The generated minimum value MIN' issupplied to an output terminal 87 through a register 86.

A value 2^(n) predetermined corresponding to the number of quantizingbits used in the quantizing step width calculating portion 6 is suppliedto a terminal 88. The multiplying device 89 multiplies the value 2^(n)supplied from the terminal 88 (where n is the number of quantizing bits)by the data ((mΣxy-ΣxΣy)/(mΣx² -(Σx)²)) and supplies output value asdata (2^(n) (mΣxy-ΣxΣy)/(mΣx² -(Σx) ²) ) that is an optimized dynamicrange DR'. The generated dynamic range DR' is supplied to an outputterminal 93 through registers 90, 91, and 92. Thus, the optimizedminimum value MIN' and the optimized dynamic range DR' can be obtained.

FIGS. 5A and 5B are block diagrams showing a structure of a pictureencoding apparatus according to a second embodiment of the presentinvention. In the picture encoding apparatus according to the secondembodiment, along with quantized values, an optimized maximum value MAX'and an optimized dynamic range DR' are transmitted. For simplicity, inthe second embodiment, similar portions to those in the first embodimentare denoted by similar reference numerals and their description isomitted.

A subtracting portion 19 subtracts each of the input pixel values y(composed of 8 bits) of nine pixels of each block of (3×3) pixels fromthe maximum value MAX and normalizes the input pixel values of the 9pixels. The normalized pixel values of the 9 pixels are supplied to aquantizing portion 7. The quantizing portion 7 supplies the quantizedvalues (composed of 4 bits) of the 9 pixels of the block of (3×3) pixelsto a least squares method based estimating portion 9 and a framingportion 11.

Input pixel values y of 9 pixels of the block of (3×3) pixels as aninput pixel signal and the quantized pixel values x of the 9 pixels ofthe block of (3×3) pixels are supplied to the least, squares methodbased estimating circuit 9. The least squares method based estimatingcircuit 9 estimates an optimized dynamic range DR' and an optimizedmaximum value MAX' with the input pixel values (true values) y and thequantized values y' for each block corresponding to the least squaresmethod in such a manner that the sum of square of the error (y'-y) ofthe decoded values y' of the quantized values of the pixels and the truevalues y thereof becomes minimum. In other words, the relation expressedby the following formula (5) is satisfied between the decoded values y'of the input pixel values and the quantized values x.

    y'=MAX-x×DR/n                                        (5)

(where n is the number of quantizing bits)

When the number of pixels of each block is denoted by m, the optimizeddynamic range DR' can be obtained corresponding to the formula (2) withthe formula (3). On the other hand, the optimized maximum value MAX' canbe obtained corresponding to the following formula (6) with the formula(3). ##EQU1##

The optimized dynamic range DR' and the optimized maximum value MAX' aresupplied to the framing portion 11. The framing portion 11 frames thequantized values x supplied from the quantizing portion 7, the optimizeddynamic range DR' supplied from the least squares method basedestimating portion 9, and the optimized maximum value MAX' suppliedtherefrom for each block.

FIGS. 6A and 6B are block diagrams showing a structure of a pictureencoding apparatus according to a third embodiment of the presentinvention. In the picture encoding apparatus according to the thirdembodiment, along with quantized pixel values, an optimized maximumvalue MAX', and an optimized minimum value MIN' are transmitted. Forsimplicity, in the third embodiment, similar portions to those in thefirst embodiment are denoted by similar reference numerals and theirdescription will be omitted.

As with the second embodiment, a subtracting portion 5 subtracts theminimum value MIN from each of input pixel values y (composed of 8 bits)of 9 bits of each block of (3×3) pixels and normalizes the pixel valuesof the 9 pixels. The normalized pixel values of the 9 pixels aresupplied to a quantizing portion 7.

The quantizing portion 7 supplies quantized values (composed of 4 bits)of the 9 bits of the block of (3×3) pixels to a least squares methodbased estimating portion 10 and a framing portion 11. Input pixel valuesy of 9 pixels of each block of (3×3) pixels as an input picture signaland the quantized pixel values x of the 9 pixel of each block of (3×3)pixels are supplied to the least squares method based estimating portion10. The least squares method based estimating portion 10 estimates anoptimized minimum value MIN' and an optimized maximum value MAX' withthe input pixel values (true values) y and the quantized values x foreach block corresponding to the least squares method in such a mannerthat the sum of square of the error (y'-y) of the decoded values y' ofthe quantized values and the true values thereof becomes minimum. Inother words, the relation expressed by the following formula (7) issatisfied between the decoded values y' of the input pixel values y andthe quantized values x.

    y'=x×(MAX-MIN)/n+MIN                                 (7)

(where n is the number of quantizing bits)

When the number of pixels of each block is denoted by m, the optimizedminimum value MIN'can be obtained corresponding to the formula (4) withthe formula (3). The optimized maximum value MAX' can be obtainedcorresponding to the formula (6) with the formula (3). The optimizedminimum value MIN' and the optimized maximum value MAX' are supplied tothe framing portion 11. The framing portion 11 frames the quantizedvalues x supplied from the quantizing portion 7, the optimized minimumvalue MIN' supplied from the least squares method based estimatingportion 10, and the optimized maximum value MAX' supplied therefrom foreach block.

FIG. 7 is a block diagram showing a structure of a hierarchical encodingapparatus for which a pixel encoding apparatus according to the presentinvention is applied. An input picture signal is supplied from an inputterminal 101 to an average calculating portion 102 and a subtractingportion 104. The average calculating portion 102 adds 4 pixels as ablock of (4 ×4) pixels of the input picture signal and divides the addedvalue by 4 and outputs an average pixel value. The average pixel valueis supplied to an interpolating portion 103 and a highly efficientencoding portion 108.

The interpolating portion 103 interpolates pixels (which were thinnedout by the average calculating portion 102) corresponding to for examplea class category adaptive process technology and supplies the resultantpixels to a subtracting portion 104. The interpolating methodcorresponding to the class category adaptive process technology has beenproposed by the applicant of the present patent application as forexample Japanese Patent Laid-Open Publication No. 5-328185 laid open onDec. 3, 1993. The U.S. patent application Ser. No. 08/061,730 filed onMay 17, 1993 corresponds to such a Japanese patent application. Itshould be noted that the interpolating portion 103 may correspond to anyknown interpolating method other than the class category adaptiveprocessing technology.

The subtracting portion 104 subtracts interpolated pixels from the inputpixel values y and supplies the resultant difference signal to a highlyefficient encoding portion 105. As with the above-described embodimentsof the present invention, the highly efficient encoding portion 105 is ahighly efficient encoding portion corresponding to the ADRC method thatoptimizes at least two parameters of a dynamic range DR, a minimum valueMIN, and a maximum value MAX.

In other words, the highly efficient encoding portion 105 generatesquantized values x and additional codes (for example, the optimizeddynamic range DR' and the optimized minimum value MIN' in the firstembodiment) and supplies the generated quantized values x and additionalcodes to a variable-length-code encoding portion 106. Thevariable-length-code encoding portion 106 performs avariable-length-code encoding process (such as Huffman-code encodingprocess or run-length-code encoding process) for the supplied quantizedvalues x and the additional codes. The variable-length-code encoded datais supplied as encoded data of a lower hierarchical level to an outputterminal 107.

Likewise, the averaged pixel value is supplied from the averagecalculating portion 102 to the highly efficient encoding portion 108.The highly efficient encoding portion 108 is a highly efficient encodingportion corresponding to the ADRC method that optimizes at least twoparameters of the dynamic range DR, the minimum value MIN, and themaximum value.

In other words, the highly efficient encoding portion 108 generates thequantized values x and additional codes (for example, the optimizeddynamic range DR' and the optimized minimum value MIN' in the firstembodiment) and supplies the generated quantized values x and theadditional codes to a variable-length-code encoding portion 109. Thevariable-length-code encoding portion 109 performs avariable-length-code encoding process (such as Huffman-code encodingprocess or run-length-code encoding process) for the supplied quantizedvalues x and the additional codes and supplies the variable-length-codeencoded data as encoded data of a higher hierarchical level to an outputterminal 110.

According to the first, second, and third embodiments of the presentinvention, as parameters to be transmitted, at least two of theoptimized dynamic range DR', the optimized minimum value MIN', and theoptimized maximum value MAX are used. However, in the present invention,the parameters to be transmitted are not limited to such parameters.Instead, two parameters including at least an optimized quantizing stepwidth Δ' can be transmitted.

In other words, according to the present invention, the least squaresmethod based estimating portion optimizes at least two parameters andtransmits the two optimized parameters along with quantized values.

In the first and third embodiments of the present invention, thesubtracting portion 5 subtracts the minimum value MIN from each ofquantized values of 9 pixels. However, the present invention is notlimited to such a structure. Instead, as with the second embodiment, thesubtracting portion 5 may subtract each of input pixel values of 9pixels from the maximum value MAX.

According to the second embodiment of the present invention, thesubtracting portion 19 subtracts each of quantized values of 9 pixelsfrom the maximum value MAX. However, the present invention is notlimited to such a structure. As with the first embodiment, thesubtracting portion 19 may subtract the minimum value from each ofquantized values of 9 pixels.

Moreover, the block dividing portion according to the present inventiondivides an input picture signal into two-dimensional blocks each ofwhich is composed of (3×3) pixels. However, the present invention is notlimited to such a block structure. In other words, each block may becomposed of other than (3×3) pixels. Alternatively, the input picturesignal may be composed of three-dimensional blocks.

Furthermore, according to the above-described embodiments of the presentinvention, the ADRC method is used. Instead, according to the presentinvention, the DCT (Discrete Cosine Transform) method may be used. Inthis case, a DC component is optimized. Moreover, according to thepresent invention, the GBTC (Global Block Truncation Coding) method maybe used. In this case, an average value and a standard deviation may beoptimized.

In addition, according to the above-described embodiments of the presentinvention, the encoding apparatus encodes a digital picture signal.However, the present invention is not limited to such apparatus.Instead, the present invention may be applied for an encoding apparatusthat encodes data such as a digital audio signal.

According to the present invention, on the encoding side, parameters forobtaining quantized values are optimized corresponding to the leastsquares method in such a manner that a decoded error between originalsignal values and restored values becomes minimum. Thus, according tothe present invention, the error between the restored values and theoriginal signal values is decreased on the decoding side.

Although the present invention has been shown and described with respectto best mode embodiments thereof, it should be understood by thoseskilled in the art that the foregoing and various other changes,omissions, and additions in the form and detail thereof may be madetherein without departing from the spirit and scope of the presentinvention.

What is claimed is:
 1. A picture record medium for recording an encodedsignal of which an input digital picture signal has been encoded in sucha manner that the amount of generated data of the input digital data isreduced, the picture record medium having a record region for recordingthe encoded signal, the encoded signal including:encoded data obtainedby dividing the input digital picture signal into blocks, each of whichis composed of a plurality of pixels, and encoding the pixels of each ofthe blocks, and at least one of an optimized dynamic range and minimumvalue obtained by optimizing at least one of a dynamic range and minimumvalue generated for each of the blocks in such a manner that the sum ofsquare of a decoded error of the encoded data becomes minimum.
 2. Apicture record medium for recording an encoded signal of which an inputdigital picture signal has been encoded in such a manner that the amountof generated data of the input digital data is reduced, the picturerecord medium having a record region for recording the encoded signal,the encoded signal including:encoded data obtained by dividing the inputdigital picture signal into blocks, each of which is composed of aplurality of pixels, and encoding the pixels of each of the blocks, andan optimized parameter obtained by optimizing a parameter generated foreach of the blocks in such a manner that the sum of square of a decodederror of the encoded data becomes minimum, wherein the encoded data isquantized values of the pixels obtained by detecting the maximum valueand the minimum value of the pixels of each of the blocks, detecting adynamic range that is the difference between the maximum value and theminimum value, and quantizing pixel values of the pixels that have beennormalized with the value of the dynamic range, and wherein theoptimized parameter is obtained by the optimizing the parameter of eachof the blocks in such a manner that the sum of square of a decoded errorof the quantized values becomes minimum.
 3. A picture record medium forrecording an encoded signal of which an input digital picture signal hasbeen encoded in such a manner that the amount of generated data of theinput digital data is reduced, the picture record medium having a recordregion for recording the encoded signal, the encoded signalincluding:encoded data obtained by dividing the input digital picturesignal into blocks each of which is composed of a plurality of pixelsand encoding the pixels of each of the blocks, and an optimizedparameter obtained by optimizing a parameter generated for each of theblocks in such a manner that the sum of square of a decoded error of theencoded data becomes minimum, wherein the optimized parameter is aparameter obtained by optimizing at least two of informationrepresenting the maximum value, the minimum value, and the dynamic rangeof the pixels of each of the blocks in such a manner that the sum ofsquare of a decoded error of the quantized values becomes minimum.